Macroevolution

Isolation Factors

Geographical Isolation

Due to being isolated on the Galapagos islands, marine iguanas are not physically capable to swim or travel far enoguh to different islands.

Reproductive Isolation

Another isolation factor is reproductive isolations, because mating depends on the size of the iguana, smaller sized subspecies will not attract partners from the bigger sized subspecies, causing no offspring between the two subspecies. The males also fight with each other during mating season, so smaller iguanas also has a smaller chance of winning fights.

Mechanisms of macroevolution

Local Adaptation

Another key factor of macroevolution is local adaptation, remember the ancestors of marine iguanas were originally land iguanas, so through generations of evolution. These land iguanas gradually gained aquatic traits such as swimming, sneezing out excess salt, having a snout nose, etc; which helped them having a better chance of survival on the Galapagos. This led to the speciation of the marine iguanas, diverging for their ancestors, and ultimately making a new specie.

Interspecies Relationships

Mutualism

Symbiotic relationship is shared between lava lizards and marine iguanas. Lava lizards eat dead skin off of the marine iguanas to help their diet. Not only that they help get rid of flies around the marine iguana. This relationship is a form of mutualism. Mutualism (one of the types of symbiotic relationship) meaning both get fair benefits from each other. The marine iguana is cleaned and unbothered by flies, while the lava lizard gets it's source of food.